Non-linear spatial summation in cat retinal ganglion cells at different background levels

R. A. Linsenmeier*, H. G. Jakiela

*Corresponding author for this work

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Cat retinal ganglion cells were identified as X-cells (linear) or Y-cells (non-linear) on the basis of the spatial summation properties of their receptive fields. For each cell, the degree of non-linearity in spatial summation was assessed at a number of different mean luminance levels in order to determine how spatial linearity depended on mean luminance. The stimuli were counterphase sinusoidal gratings whose contrast was sinusoidally modulated in time. A grating with one bar centered on the receptive field was used to measure the contrast sensitivity of the mechanisms which produced responses at the stimulus frequency. A grating with a zero crossing centered on the receptive field was used to measure the contrast sensitivity of mechanisms responsible for the non-linear frequency doubled responses of Y-cells. As the mean luminance was reduced from low photopic to scotopic, the contrast sensitivity decreased for both the linear and non-linear responses. The ratio of non-linear to linear sensitivity in Y-cells changed less with background than did either contrast sensitivity. In some Y-cells this ratio decreased slightly at low luminance levels, but in others it did not. X-cells appeared to sum signals linearly at all levels of illumination. X-cells and Y-cells could still be distinguished on the basis of their spatial summation properties in the scotopic range.

Original languageEnglish (US)
Pages (from-to)301-309
Number of pages9
JournalExperimental Brain Research
Volume36
Issue number2
DOIs
StatePublished - Jul 1 1979

Keywords

  • Retinal Ganglion Cells
  • X-cells/Y-cells

ASJC Scopus subject areas

  • Neuroscience(all)

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